Abstract
Background
Echocardiography remains a key noninvasive cardiac investigative tool in the management of patients, especially in a developing economy like Nigeria. In this study, we investigated the indications for transthoracic echocardiography and spectrum of cardiac disease found in patients referred to our cardiac unit for echocardiography.
Methods
A prospective two-dimensional, pulsed, continuous, and color-flow Doppler echocardiographic evaluation was done using the transthoracic approach in 2501 patients over an eight-year period. Univariate data analysis was performed for mean age, gender, clinical indications, and diagnoses.
Results
The subject age range was less than 12 months to 97 years (mean 52.39 years). There were 1352 (54.06%) males and 1149 (45.94%) females. The most common indication for echocardiography was hypertension (52.1%) followed by congestive cardiac failure (13.9%). Others were for screening (6.1%), arrhythmias (5%), cerebrovascular disease (5%), chest pain (3.3%), chronic kidney disease (3.2%), congenital heart disease (2.6%), cardiomyopathy (1.8%), rheumatic heart disease (1.7%), diabetes mellitus (1.3%), thyrocardiac disease (1.2%), ischemic heart disease (1.2%), and pericardial disease (1.1%). The echocardiographic diagnosis was hypertensive heart disease in 59.4% of subjects and normal in 14.1%. Other echocardiographic diagnoses included rheumatic heart disease (3.1%), congenital heart disease (2.1%), cardiomyopathy (1.7%), pericardial disease (1.1%), and ischemic heart disease (0.1%).
Conclusion
Hypertension and its cardiac complications is the most common echocardiographic indication and diagnosis at our unit.
Keywords: echocardiography, cardiac diseases, prospective, indications, diagnosis, Nigeria
Introduction
Echocardiography remains a key noninvasive investigative tool in the current management of cardiac patients, especially in a developing economy like Nigeria. It is undoubtedly the fifth dimension in cardiovascular examination after inspection, palpation, percussion, and auscultation.1 It gives relevant morphological and hemodynamic information which often guides the management of cardiac patients.2,3 The field of echocardiography is rapidly expanding from the use of M-mode in the 1950s to three-dimensional, Doppler, and transesophageal echocardiography in present day cardiology.4 This cost-effective modality of cardiac assessment has a high degree of sensitivity and specificity, and when performed by a trained operator is second only to electrocardiography.5 There is a strong correlation between echocardiographic findings and those of cardiac catheterization and radionuclide studies.6,7
The widespread availability of and accessibility to echocardiographic services in the Western world have greatly enhanced the classification and effective management of cardiovascular disease.8 This is not so in Nigeria, despite increasing availability in many tertiary health care facilities due to high cost and concentration of facilities in the urban centers.9 Understanding the pattern of cardiac disease is important in strategic planning of the use of scarce resources in the management of affected patients and preventive interventions to reduce the burden of disease.
To date, there are only a few reports in Nigeria of two-dimensional and Doppler echocardiographic evaluation in which a large number of patients with cardiac disease were studied.8,10,11 A study of this nature at our tertiary health facility in South-West Nigeria in a large population of patients would give a more balanced view of the frequencies of these echocardiographically diagnosed cardiac diseases in Nigeria. This will further complement the available information on echocardiographic studies at the global level.
Therefore, we undertook a prospective eight-year study of two-dimensional, pulsed, continuous, and color-flow Doppler transthoracic echocardiographic evaluation of 2501 patients referred for echocardiography to the cardiac care unit of a tertiary hospital in South-West Nigeria. This will help to define further the pattern of cardiac disease in our environment, and also add to the national and global database.
Materials and methods
We studied echocardiograms for 2501 of 2517 patients referred from south-western states with cardiac complaints during 2002–2010. Two-dimensional, M-mode, color, pulsed and continuous wave Doppler transthoracic echocardiographic examinations were performed with a Sonoline G60 S ultrasound imaging system (Siemens Medical Solutions USA Inc, Malvern, PA, USA) using standard procedures.12,13 Ethical clearance was obtained for the study from the Ethics and Research Committee of Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.
Statistical analysis
Continuous variables are expressed as the mean ± standard deviation, with frequency expressed as a percentage. All statistical analyses were performed using the commercially available Statistical Package for the Social Sciences version 15 software (SPSS Inc, Chicago, IL, USA).
Results
Of the 2501 patients included, 1352 (54.06%) were male and 1149 (45.94%) were female, with a male to female ratio of 1.2:1. The mean age was 52.39 ± 17.73 years, with a median and mode of 55 years and 60 years, respectively. Most of the referrals came from the center’s cardiology outpatient clinics and adult medical wards, internal medicine, family medicine, surgery, and pediatrics. The clinical indications for echocardiography are shown in Table 1. The most common indication was hypertension (52.1%) followed by congestive cardiac failure (13.9%). Table 2 shows the echocardiographic findings, with the most common diagnosis being hypertensive heart disease (59.4%), with normal findings in 14.1% of subjects. The echocardiographic confirmation rate of clinical diagnoses in Table 3 shows higher sensitivity for hypertensive heart disease, congestive cardiac failure, rheumatic heart disease, and valvular heart disease.
Table 1.
Clinical indications for echocardiography
| Clinical indication | Requests (n) | Percentage |
|---|---|---|
| Systemic hypertension | 1311 | 52.1 |
| Congestive cardiac failure | 347 | 13.9 |
| Medical screening | 154 | 6.1 |
| Cerebrovascular disease | 88 | 5 |
| Arrhythmia | 87 | 5 |
| Chest pain | 82 | 3.3 |
| Chronic kidney disease | 80 | 3.2 |
| Congenital heart disease | 68 | 2.6 |
| Cardiomyopathy | 46 | 1.8 |
| Alcoholic heart disease | 43 | 1.7 |
| Rheumatic heart disease | 42 | 1.7 |
| Diabetic mellitus | 32 | 1.3 |
| Thyrotoxic heart (or thyrocardiac) disease | 30 | 1.2 |
| Ischemic heart disease | 31 | 1.2 |
| Pericardial disease | 29 | 1.1 |
| Valvular heart disease | 11 | 0.4 |
| Malignancy (prechemotherapy) | 8 | 0.3 |
| Infective endocarditis | 6 | 0.2 |
| Obstructive uropathy | 3 | 0.1 |
| Peripheral vascular disease | 3 | 0.1 |
| Total | 2501 | 100 |
Table 2.
Echocardiographic diagnoses
| Diagnosis | Patients (n) | Percentage |
|---|---|---|
| Hypertensive heart disease | 1494 | 59.4 |
| Congestive cardiac failure | 401 | 16.0 |
| Normal study | 355 | 14.1 |
| Rheumatic heart disease | 78 | 3.1 |
| Congenital heart disease | 54 | 2.1 |
| Cardiomyopathy | 42 | 1.7 |
| Pericardial disease | 28 | 1.1 |
| Thyrotoxic heart (or thyrocardiac) disease | 14 | 0.6 |
| Valvular heart disease | 12 | 0.5 |
| Infective endocarditis | 3 | 0.1 |
| Ischemic heart disease | 2 | 0.1 |
| Inconclusive | 18 | 0.7 |
| Total | 2501 | 100 |
Table 3.
Echocardiographic confirmation rate of clinical diagnoses
| Clinical diagnoses | Requests | Confirmed by echocardiography (n) | Percentage |
|---|---|---|---|
| Systemic hypertension | 1311 | 1494 | 114 |
| Congestive cardiac failure | 347 | 401 | 116 |
| Rheumatic heart disease | 42 | 78 | 186 |
| Congenital heart disease | 68 | 54 | 79 |
| Cardiomyopathy | 46 | 42 | 91 |
| Pericardial disease | 29 | 28 | 97 |
| Thyrotoxic heart (or thyrocardiac) disease | 30 | 14 | 47 |
| Valvular heart disease | 11 | 12 | 109 |
| Infective endocarditis | 6 | 3 | 50 |
| Ischemic heart disease | 31 | 2 | 6.5 |
Discussion
The results of this study show that systemic hypertension and its cardiac complications is the most common indication for echocardiography as well as the most common echocardiographic diagnosis at our center. These findings are similar to reports from other hospitals in Nigeria,3,14,15 where the prevalence of hypertension is high and increasing.16,17 However, similar research in Enugu reported valvular heart disease to be the most common indication for echocardiography and diagnosis, ahead of hypertensive heart disease.11 This may reflect the fact that there is an active cardiac surgical unit at the hospital in Enugu, thereby attracting more referrals for patients with structural heart disease.8 Ischemic heart disease was diagnosed in 0.1% of the subjects in our study, with a significant proportion of patients having a normal echocardiogram. This low prevalence is consistent with earlier studies, despite the reported rising incidence of coronary artery disease in developing countries like Nigeria.18,19 Balogun et al,3 Ukoh and Omuemu,14 and Ike11 reported respective coronary artery disease prevalence rates of 2%, 2.7%, and 0.8%. Thyrotoxic heart disease or thyrocardiac disease20 was diagnosed in 0.6% of subjects with an echocardiographic confirmation rate of 47%. Thyrocardiac disease refers to thyrotoxic patients with cardiac complications, such as congestive heart failure or persistent cardiac dysrhythmia.20,21 The concept of thyrotoxic heart disease or thyrocardiac disease was probably first introduced by Levine et al, based on their observations of patients in whom thyrotoxicosis was the major factor leading to cardiomegaly, atrial fibrillation,22 or congestive heart failure.23
The echocardiographic confirmation rate of clinical diagnoses shows high sensitivity for hypertensive heart disease, congestive cardiac failure, rheumatic heart disease, and valvular disease, as also reported by Kolo et al.8
Conclusion
Hypertension was the most common echocardiographic indication in our cardiac care unit, and hypertensive heart disease was the most common echocardiographic diagnosis. Congestive cardiac failure was the next most common indication and echocardiographic diagnosis. Echocardiographic confirmation of clinical diagnoses showed higher sensitivity for hypertensive heart disease and congestive cardiac failure.
Footnotes
Disclosure
This paper was presented at the 36th Annual General and Scientific Meeting of the West African College of Physicians held at the Ghana Institute of Management and Public Administration, Accra, Ghana, held on November 2–8, 2012. Otherwise, the authors report no conflicts of interest in this work.
References
- 1.Luthra A. Echo Made Easy. 2nd ed. New Delhi, India: Jaypee Brothers Medical Publishers Ltd; 2007. [Google Scholar]
- 2.Balogun MO, Omotoso ABO, Bell E, et al. An audit of emergency echocardiography in a district general hospital. Int J Cardiol. 1993;41:65–68. doi: 10.1016/0167-5273(93)90137-6. [DOI] [PubMed] [Google Scholar]
- 3.Balogun MO, Urhogide GE, Ukoh VA, Adebayo RA. A preliminary audit of two-dimensional and Doppler echocardiographic services in a Nigerian tertiary private hospital. Niger J Med. 1999;8:139–141. [Google Scholar]
- 4.Elder I, Lindstrom K. The history of echocardiography. Ultrasound Med Biol. 2004;30:1565–1644. doi: 10.1016/S0301-5629(99)00056-3. [DOI] [PubMed] [Google Scholar]
- 5.Cheitlin MD, Armstrong WF, Aurigemma AG, et al. ACC/AHA/ASE guideline update for the clinical application of echocardiography: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASE Committee to update the 1997 Guidelines for the Clinical Application of Echocardiography) J Am Coll Cardiol. 2003;42:954–970. doi: 10.1016/s0735-1097(03)01065-9. [DOI] [PubMed] [Google Scholar]
- 6.Appleton CP, Hatle LK, Popp RL. Relation of transmittal flow velocity patterns to left ventricular diastolic dysfunction: new insights from a combined hemodynamic and Doppler echocardiographic study. J Am Coll Cardiol. 1988;12:426–440. doi: 10.1016/0735-1097(88)90416-0. [DOI] [PubMed] [Google Scholar]
- 7.Rakowski HC, Appleton KL, Chan JG, et al. Canadian consensus recommendations for the measurement and reporting of diastolic dysfunction by echocardiography. J Am Soc Echocardiogr. 1996;9:736–760. doi: 10.1016/s0894-7317(96)90076-0. [DOI] [PubMed] [Google Scholar]
- 8.Kolo PM, Omotoso ABO, Adeoye PO, et al. Echocardiography at the University of Ilorin Teaching Hospital, Nigeria: a three years audit. Res J Med Sci. 2009;3:141–145. [Google Scholar]
- 9.Ogah OS, Adebanjo AT, Otukoya AS, Jagusa TJ. Echocardiography in Nigeria: use, problems, reproducibility and potentials. Cardiovasc Ultrasound. 2006;4:13. doi: 10.1186/1476-7120-4-13. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Ogah OS, Adegbite GD, Akinyemi RO, et al. Spectrum of heart diseases in a new cardiac service in Nigeria: an echocardiographic study of 1441 subjects in Abeokuta. BMC Res Notes. 2008;1:98. doi: 10.1186/1756-0500-1-98. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Ike SO. Echocardiographic analysis of valvular heart diseases over one decade in Nigeria. Trans R Soc Trop Med Hyg. 2008;102:1214–1218. doi: 10.1016/j.trstmh.2008.06.008. [DOI] [PubMed] [Google Scholar]
- 12.Schiller NB, Crawford M. Recommendations for quantitation of 2-dimensional echocardiography: American Society of Echocardiography Committee on standards, subcommittee on quantitation of two-dimensional echocardiograms. J Am Soc Echocardiogr. 1989;2:358–367. doi: 10.1016/s0894-7317(89)80014-8. [DOI] [PubMed] [Google Scholar]
- 13.Quinones MA, Otto MC, Waggoner A, Zoghbi WA. Recommendation for the quantification of Doppler echocardiography. A report from the Doppler Quantification Task Force of the Nomenclature and Standards Committee of the American Society of Echocardiography. J Am Soc Echocardiogr. 2002;15:167–184. doi: 10.1067/mje.2002.120202. [DOI] [PubMed] [Google Scholar]
- 14.Ukoh VA, Omuemu C. Spectrum of heart diseases in adult Nigerians: an echocardiographic study. Nigerian Journal of Cardiology. 2005;2:24–27. [Google Scholar]
- 15.Agomuoh DI, Akpa MR, Alasia DD. Echocardiography in the University of Port Harcourt teaching hospital Apr 2000 to May 2003. Niger J Med. 2006;15:132–136. doi: 10.4314/njm.v15i2.37096. [DOI] [PubMed] [Google Scholar]
- 16.Ekwunife OI, Aguwa CN. A meta analysis of prevalence rate of hypertension in Nigerian populations. J Public Health Epidemiol. 2011;13:604–607. [Google Scholar]
- 17.Adedoyin RA, Mbada CE, Balogun MO, et al. Prevalence and pattern of hypertension in a semi-urban community in Nigeria. Eur J Cardiovasc Prev Rehabil. 2008;15:683–687. doi: 10.1097/HJR.0b013e32830edc32. [DOI] [PubMed] [Google Scholar]
- 18.Akinboboye OO, Idris OA, Akinkugbe O. Trends in coronary artery disease and associated risk factors in Sub-Saharan Africans. J Hum Hypertens. 2003;17:381–387. doi: 10.1038/sj.jhh.1001562. [DOI] [PubMed] [Google Scholar]
- 19.Sani MU, Adam B, Mijinyawa MS, et al. Ischaemic heart disease in Aminu Kano Teaching Hospital, Kano Nigeria: a 5 year review. Niger J Med. 2006;15:128–131. doi: 10.4314/njm.v15i2.37095. [DOI] [PubMed] [Google Scholar]
- 20.Kolawole BA, Balogun MO. Thyrotoxicosis and the heart – a review of the literature. Niger J Med. 2001;10:50–54. [PubMed] [Google Scholar]
- 21.Hamburger JL. Clinical Exercises in Internal Medicine. Vol. 1. Philadelphia, PA: WB Saunders Co; 1978. Thyroid diseases. [Google Scholar]
- 22.Levine SA, Sturgis CC. Hyperthyroidism masked as heart disease. Boston Med Surg J. 1924;190:233–237. [Google Scholar]
- 23.Likoff WB, Levine SA. Thyrotoxicosis as the sole cause of heart failure. Am J Med Sci. 1943;206:425–435. [Google Scholar]